Earplug



E. S. MENDELSON Nov. 12, 1963 EAR PLUG Filed April 14, 1961 IIEE EE Z'1' Q $5M INVENTOR. Emanuel Mendelson BY AGENT L. 16%

ATTORNEY of the receiver and the ear canal.

United States Patent 3,116,356 EARPLUG Emanuel S. Mendelsun, RD. 1, hex34d, Harleysville, Pa. Filed Apr. 14, 1961, Ser. No. M3,???

1 Claim. or. ran-2 s (Granted under Title 35, U5. @ode {1%52), sec. 266

The invention described herein may be manufactured and used by or forthe Government for governmental purposes without the payment of anyroyalty thereon.

This invention is directed to acoustic devices and is more particularlydirected to the provision of an ear insert for acoustically coupling asound outlet opening of a sound transmitting device, such as ahearing-aid earphone or the like, to the ear canal and for theprevention of the direct transmission of sound thereto.

Previously, I have designed an earplug which fits into the auditorymeatus of the car. This plug takes the form of a hollow shell which issufficiently pliable so that it readily adapts itself to the contour ofthe ear canal. Since the plug is composed of latex and since asubstantial portion of the sidewall of the plug makes frictionalengagement with the sidewalls of the canal, it was possible to form anhermetic seal between the outer wall of the plug and the inner surfaceof the auditory meatus by maintaining a quantity of fluid in the hollowshell at a pressure slightly above atmospheric pressures at normal bodytemperatures thereby imparting elasticity to the thin shell.

Although the broad, general principles utilized in the hearing guardhave proven to be sound in every respect, and the structure thereindisclosed has been used to great advantage, it has been discovered thatby making certain structural changes of relatively small significancefrom the standpoint of manufacturing costs significant improvements inoperating results can be obtained.

Various forms of ear inserts for acoustically coupling a sound outletopening of a sound transmitting device to the auditory meatus of aperson have been suggested in the past. In hearing-aid earphones inconnection with which car inserts are most commonly used, most of theear inserts are made of a hard synthetic resin material and molded froma plaster cast so as to fit the outer ear cavity in order to establish aseal between the sound outlet In addition the insert serves to supportthe receiver on the ear or" the user.

These plugs were designed to control the transmission of sound in suchmanner as to prevent excessive sounds such as caused by a bomb explosionor gun concussion from injuring the ear organs While permitting normalsound to be transmitted to the hearing center of the user. Variousattempts have been made in the past to provide a universally adjsutableear insert device. However, individual ears differ greatly in size andshape and have outer ear cavities of greatly varying configurationsthereby making it extremely difficult to effect a good acoustic sealbetween the ear insert device and the outer ear, and resulting in leaks.

Leaking earplugs fail to exclude sounds of low frequency. The effect ofan earplug leak is known to be that it acts as a low pass acousticfilter, attenuating the passage of incident sounds only above acharaceristic cutoff frequency. The more minute the leak, the lower thecut-off frequency and hence the less the attenuation penalty. However,the low end of the sonic spectrum is a particularly dangerous area,since the power plants used for the propulsion of high performance jetaircraft generate their most intense noise peaks at low frequencies.Another general effect of incomplete noise exclusion is that anyentrance of ambient sounds within the speech or communications signalrange may either mask the needed communications information or appear todistort it. The

3,1 ld i'i h Patented Nov. 12, l63

proposition that the wearers ear canal should be completely sealed offfrom the ambient environment about the head may therefore be grantedgeneral acceptance in many types of operational use. However, when theear is so completely sealed off and when the wearer then experiencessome marked change in ambient pressure or temperature, the tendencytoward change in volume Within the enclosed space or spaces next to thecanal or eardrum may induce undesired pressure reactions withinrestricted portions of the system. These pressure changes will dependupon precise conditions, but their effects would range between outwardexpulsion of the plug with loss of its desired function, and inwardpropulsion of the plug possibly attended by pain and damage to thesensitive tissues of the ear canal and tympanic membrane. Specificdiiiiculties of these types experienced by plugs under the prior arthave obstructed the use of well sealed ear protectors by aviators andother personnel who may be eirposed to dangerously intense noisecombined with changes in barometric pressure.

Accordingly, an object of this invention is to provide a communicationsearplug system which possesses means for the transmission of soundthrough the body of the earplug, and means for inflating, deflating theplug to allow for pressure adjustment to compensate for changingenvironmental or operational requirements.

Another object of this invention is to provide an earplug whichpossesses central stiffness, lateral thinness and stretch whereby it ismade to conform to the shape of the wearers ear canal without painfuldistension while forming a hermetric seal. Yet another object of thisinvention is to provide an earplug capable of resisting sudden pressurechanges with a minimum of exposed area and provided with means forhearing conversation in combination with means for equalizing airpressure in the outer ear canal.

A still further object of this invention is to provide means forestablishing a good acoustic seal between the sound outlet of a receiverattached to the ear insert and the ear canal, wherein the insert alsoserves to support the receiver on the ear of the user.

Various other objects and advantages will be apparent from the followingdescription of one embodiment of the invention, and the novel featureswill be particularly pointed out hereinafter in connection with theappended claim.

In the accompanying drawing:

FIG. 1 is an enlarged side elevational view in crosssection of anembodiment of the invention showing the plug having a transmittingdevice connected thereto.

FIG. 2 is a view similar to FIG. 1 wherein the transmitting device hasbeen disconnected from the plug and means are shown for adjusting thepressure in the outer periphery of the plug.

FIG. 3 is a front sectional view of a helmet showing how thecommunications earplug system works in its intended environment.

The ear insert arrangements of the present invention, the various novelfeatures or" which will be described hereinafter in connection withspecific exemplifications thereof, overcome the diiiiculties encounteredwith prior art adjustable ear inserts whereby it is possible to fit earsof a great variety of configurations and sizes with only a few sizes ofear inserts of one standard construction.

Referring to FIGS. 1 and 2, a sound transmitting device 1 is fitted toan ear insert member 3, shaped for insertion into the auditory meatus ofan ear. The member 3 is made of a soft, flexible material such as latexor the like, which enables it to be tightly fitted into the ear canalwithout danger or irritation thereof. The member 3 is tapered andunduiated along the inner portion 5 and lon itudinal axis of the member3.

terminates in an end wall 9 which is disposed close to the eardrum ofthe ear.

in order to insert the protector into the ear, the portion is startedinto the auditory canal and the member 3 manipulated with a twistingmotion so as to move portion 5 fully into the canal. Due to theflexibility of the member 3, and especially the portion 5, it is readilyinserted and removed without injury or discomfort to the ear.

The member 3 is molded or fabricated so as to form a sealed space H,bounded on the outside by the thin pliable portion 5 and on the insideby a central, longitudinal, airtight channel member 13 extending throughthe The channel member 13 has a wall 15 composed of tubular nylon woventhread,

such as parachute riser chord sleeve or the like and im- The channelvpregnated with latex rubber and cured. member 13 provides an open soundcommunicating passage through the plug member 3. The wall 15 is ofsufiicient thickness and stiffness to prevent any substantialdeformation of the cross-section of the sound passage extendingtherethrough when the channel member is bent incident to its insertioninto its operative coupling posi tion within the ear canal forcompleting an acoustically scaled sound passage between the outletopening of the sound transmitting device 1 and the mouth of the earcanal.

The base or outer end It? of member 3 consists of a circular slab oflatex or the like, having a central aperture 19 through which thechannel member 1 3 extends and also having a second substantiallysmaller transverse aperture 21 through which a filling tube 23 extends.This filling tube provides for pressure adjustment in the space ill ofthe plug 3.

A ring clamp or the like locks the end wall 27 of the sound transmittingdevice l and the outer end 17 of the plug 3 tightly together. The endwall 2? contains a plurality of holes 29 around its outer periphery. Theholes communicate with channel member 13 and permit pressure adjustmentsto be made inside of the ear canal.

A flap er valve 51 makes surface contact with the rear of Wall 27 atpoints as and 2% thereby defining an annular space 32. The valve can beadjusted to open and relieve the pressure inside of channel member 13when it exceeds a critical point. The adjustment means consists of astem 33 which protrudes from a boss member 35 located on the inner sideof valve 31. A spring means or the like 36 engages the stem 33 andcontrols movement of the valve 31. The spring means is suitably fittedinto the wall 34 of the sound transmitting device 1. (Ialibrations aremade on the stem 33 to adjust the spring whereby it will permit thevalve to move only at certain predetermined pressures andpreventing'movement of the valve at all other times. This resistanceproduced to compressive force is sutlicient to cause a practicallypermanent adjustment of the flapper valve onto the wall 2'7 as far ascompressive force is concerned thereby providing an automatic andconvenient adjustment to a particular pressure. However, the wearer isable to make a manual adjustment if the plug becomes uncomfortable.

The sound transmitting device 1 is well known in the art having aconventional diaphragm 37 connected to a solenoid arrangement Thesolenoid is energized from a power source (not shown) through lead wires39 causing the diaphragm to vibrate producing sound waves which arecarried to the eardrum through the channel 13.

FIG. 2 shows how the pressure adjustments are made in the sealed spaceH. The tube 23 terminates in a reservoir 41 containing a fluid which maybe a liquid such as oil or water. Any fluid of sufficieutly lowviscosity is suitable, so long as its presence is compatible with theother materials of the systems with which it comes into contact. Theparticular operational application for which the system is intended willdetermine the most suitable filling material. For example, the greaterL1 sound attenuating properties of heavy liquids, as con trasted withthose of light gases, would have to be considered in relation torelative weight, relative likelihood of undergoing thermal expansion orcontraction and relative expansion or contraction with changes inambient pressure.

The fluid is manually forced from reservoir 41 up into space ill byforcing the plungerSEl into the cavity 55. When the pressure is desiredto be decreased, the plunger is pulled out thereby permitting the fluidto llow back into the reservoir.

Fit 3 shows a particular environment for which the communications systemis adapted.

The cars of the subject (shown in phantom) would be checked to makecertain that the earplug 3 could be inserted and retained in the earcanal without trouble. This check would best be conducted by aspecialist who could visualize the condition of the ear canal tympanicmembrane and middle ear and who could clean wax and other foreign matterout of the caanl withoutcausing local irritation. The plug 3 ismanipulated into the ear canal as hereirrbefore described. The channelmember 13 and the tube 23 extend from the rear Wall 17. The helmet orheadpiece 59 of a pressure suit (not shown) is fitted over the head ofthe subject. The aspirator bulb or the like (at is connected to thefilling tube 23 through connecting means 63. The space 11 could beinflated by forcing the bulb 61 against the side of the helmet therebyestablishing a hermetic seal between the plug, and the ear canal. Thepressure relief valve 62; prevents the pressure in space ll fromexceeding a predetermined amount. The sound device It is connected tothe channel member 13 through the connector 63. valve, two adjustablerelief valves 6-5 and 67 permit pressure compensation inside of channelmember 13. The valves are preset to maintain the pressure inside the earcanal the same as the ambient pressure inside the headpiece. Valve 65operates as an intake valve and valve 67 operates as an exhaust valve.The valves 65, 67 and 62 are adjusted to the comfort of each individualwearer.

it will be understood that various changes in the details, materials andarrangements of parts which have been herein described and illustratedin order to explain the nature of the invention, may be made by thoseskilled in the art within the principle and scope of the invention asexpressed in the appended claim.

What I claim is:

Au earpluig providing for automatic adjustments of pressure variationsand for attenuating undesirable interferences with sound communicationsto the ear comprising an elongated flexible resilient hollow shelldefiuing'a closed chamber therein, said shell having undulations aroundits outer periphery and being adapted to fit into the auditory meatus ofan ear thereby forming a tight seal therewith; a longitudinal airtightsound communicating channel member extending through the said chamberalong its longitudinal axis; conduit means integrally formed with theouter surface of the shell; pumping means connected with the conduitmeans t-or pumping .fluid into the chamber of the shell whereby theshell is maintained tightly against the sides of the auditory meatus ofthe ear; valve means connected to the channel member for regulatingpressure variations inside the ear and spring means located on the valvemeans for maintaining pressure inside the ear constant with ambientpressures.

References Cited in the file of this patent UNITED STATES PATENTS2,437,490 Watson et al Mar. 9, 1948 2,529,562 Martin Nov. 14, 19502,876,767 Wasserman Mar. 10, 1959 2,934,160 Touson Apr. 26, 1960 Inplace of the flapper

